Hydraulic actuating means for subsurface safety valve

ABSTRACT

The improvement in a hydraulic actuator for actuating a subsurface safety valve having a metal piston connected to and actuating the valve and movable in a cylinder in which the cylinder is connected at one end to a hydraulic control fluid passageway and on the second end to pressure in the safety valve. The cylinder includes metal valve seats and metal valve elements are connected to the piston for seating on the valve seats for providing positive seals. A universal connection may be provided between the pistons and the valve elements. The piston seal may be opposing metal cups or a labyrinth seal.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation-in-part of copending patentapplication Ser. No. 06/383,897, filed June 1, 1982, entitled HydraulicActuating Means for Subsurface Safety Valve now abandoned.

BACKGROUND OF THE INVENTION

It is well known to utilize an elastomer seal in a hydraulic piston andcylinder assembly in a safety valve such as shown in U.S. Pat. Nos.4,161,219 and 4,049,052. However, elastomer seals are limited as to thetemperatures in which they can operate, the pressures which they canwithstand, the corrosive environment in which they can operate, and thelength of time before they must be replaced. Copending patentapplication Ser. No. 322,318 entitled Metal to Metal High/Low PressureSeal, filed Nov. 17, 1981, discloses a metal-to-metal seal used in apiston and cylinder actuating assembly in a subsurface safety valve.However, it is difficult to manufacture metal-to-metal seals which willseal under all pressure conditions and which will seal against gases.

The present invention is directed to a hydraulic actuating means foractuating a subsurface well safety valve which avoids the use ofelastomer seals and can be used in both high and low pressure and highand low temperature applications and in the presence of corrosive fluidsand gases.

SUMMARY

The present invention is directed to a subsurface well safety valve forcontrolling fluid flow through a well conduit which includes a housingand a valve closure member moving between open and closed positions byproviding an improved hydraulic actuating means for actuating the valveclosure member. At least one cylinder is provided in the housing with ametal piston movable in each cylinder. The piston is connected to andmoves the valve closure member. The cylinder on one side of the pistonis in communication with a hydraulic control fluid passageway and thecylinder on the second side of the piston is in communication with fluidpressure in the valve housing. The cylinder includes first and secondspaced metal valve seats. First and second metal valve elements areconnected to the piston. The first and second metal valve elements arespaced from each other to alternately seat and unseat on the first andsecond valve seats, respectively, as the piston alternately moves in thecylinder. The metal valve elements provide a positive seal for sealingoff the hydraulic actuating means even if fluid leaks by the piston.

A still further object of the present invention is wherein the pistonincludes a metal seal for sealing against the cylinder.

A further object is wherein the piston includes opposing metal cupsengaging the cylinder.

Another object is wherein the piston includes a labyrinth seal.

Still a further object of the present invention is the provision of auniversal connection between the piston and said valve elements forallowing the piston to align itself properly with the cylinder.

Still a further object is wherein the first and second valve seats areon opposite sides of the piston and the first and second valve elementsare connected to opposing sides of the piston. Preferably, the valveseats and valve elements are positioned whereby the first element isadapted to seat on the second seat when the piston moves away from thesecond seat.

Another object is the provision of another embodiment in which the firstand second valve seats are positioned on one side of the piston and thefirst and second valve elements are connected to said one side of thepiston.

Yet a still further object of the present invention is the provision ofa tubing well safety valve for controlling the fluid flow through a welltubing and including a housing having an axial bore and a valve closuremember moving in the housing between open and closed positions forcontrolling fluid flow through the bore. A longitudinally tubular memberis telescopically movable in the housing coaxially with the bore forcontrolling the movement of the valve closure member by providing animproved hydraulic actuating means for actuating the tubular member. Agenerally longitudinally extending cylinder is in the housing with theupper end of the cylinder in communication with a hydraulic controlfluid passageway, and the lower end of the cylinder is in communicationwith the pressure in the axial bore of the safety valve. A metal pistonis movable in the cylinder in response to fluid movement through thecylinder acting on the piston and the piston is connected to and movingthe tubular member. The cylinder includes an upper metal valve seat atthe upper end of the cylinder and includes a lower metal valve seat atthe lower end of the cylinder. An upper metal valve element is connectedto the piston and positioned above the upper valve seat and is adaptedto seat on the upper valve seat when the piston moves downwardly awayfrom the upper valve seat. A lower metal valve element is connected tothe piston and is positioned below the lower valve seat and is adaptedto seat on the lower valve seat when the piston moves upwardly away fromthe lower valve seat.

Other and further objects, features and advantages will be apparent fromthe following description of presently preferred embodiments of theinvention, given for the purpose of disclosure and taken in conjunctionwith the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevational view, in quarter section, of a well safetyvalve utilizing the present invention and shown in the open position,

FIG. 2 is an enlarged cross-sectional view of the hydraulic actuatingmeans of FIG. 1 with the hydraulic piston being in its full upwardposition,

FIG. 3 is an exploded perspective view of the hydraulic actuating meansof the present invention,

FIG. 3A is a modified type of piston, and

FIG. 4 is an enlarged cross-sectional view of another embodiment of ahydraulic actuating means.

DESCRIPTION OF THE PREFERRED EMBODIMENT

While the present invention will be described in connection with asubsurface tubing safety valve having a flapper type valve closuremember, it is understood that the present invention may be used withother types of safety valves and other valve closure members.

Referring now to the drawings, particularly to FIG. 1, the referencenumeral 10 generally indicates a subsurface tubing safety valve of thepresent invention which includes a body or housing 12 which is adaptedto be connected in a well tubing to permit well production therethroughunder normal operating conditions, but in which the safety valve 10 mayclose or be closed in response to abnormal conditions.

The valve 10 includes a bore 14, an annular valve seat 16 positionedabout the bore 14, a valve closure element such as a flapper valve 18connected to the body 12 by pivot pin 20. Thus, when the flapper valve18 is in the upward position and seated on the valve seat 16, the safetyvalve 10 is closed blocking flow upwardly through the bore 14 and welltubing.

A sliding tube or longitudinal tubular member 22 is telescopicallymovable in the body 12 and through the valve seat 16. As best seen inFIG. 1, when the tubular member 22 is moved to a downward position, thetube 22 pushes the flapper 18 away from the valve seat 16. Thus, thevalve 10 is held in the open position so long as the tube 22 is in thedownward position. When the tube is moved upwardly, the flapper 18 isallowed to move upwardly onto the seat 16 by the action of a spring 24and also by the action of fluid flow moving upwardly through the bore 14and behind the flapper 18.

The tubular member 22 is biased in an upward direction by a suitablemeans which may include a spring 26 for yieldably urging the member 22in an upward direction to release the flapper 18 for closing the valve10. The safety valve 10 is controlled by the application or removal of apressurized fluid, such as hydraulic fluid, through a control path orline, such as one or more control lines 32 extending to the well surfaceor the casing annulus, which supplies pressurized fluid to the top ofone or more pistons 40 which in turn act on the tubular member 22 tomove the tubular member 22 downwardly forcing the flapper 18 off of theseat 16 and into the full open position. The piston 40 may be an annularpiston or may be a plurality of circular pistons 40, such as two,positioned in the housing 12 and connected to the tubular member 22 by aconnection 42. The safety valve 10 is controlled by the application orremoval of pressurized fluid through the control lines 32 and a fluidpassageway 46 to supply hydraulic control pressurized fluid to thecylinder 48 and the top of the piston 40. The bottom of the piston 40 isexposed to fluid pressure in the bore 14 which acts against the bottomof the piston 40 for biasing the tubular member 22 to the closedposition when fluid control pressure is removed from the control line32.

The above description is generally disclosed in patent application Ser.No. 322,318 described above. However, the prior art, which has utilizeda metal piston 40, such as in the form of cup seals, is difficult tomanufacture to obtain desirable sealing under all pressure conditionsand particularly in sealing gases. Furthermore, in some applications,the metal piston 40 is subject to wear and tear in its hostileenvironment and may leak. The present invention is directed to providingpositive valve element seals connected to the piston 40 which willprovide a positive seal in both directions for the double acting piston40. And the seals will provide a working hydraulic actuator even in theevent that the piston 40 deteriorates to a condition which allows aconsiderable fluid bypass between the piston 40 and cylinder 48.

Referring now to FIG. 2, the cylinder 48 includes a first metal valveseat 50 on one side of the piston 40 and in communication with the fluidcontrol passageway 46 whereby hydraulic control fluid can flow to andactuate the top of the piston 40 through the valve seat 50. A secondmetal valve seat 52 is provided on the cylinder 48 on the second side ofthe piston 40 through which fluid pressure in the safety valve andtubing can flow to the bottom side of and actuate the piston 40. A firstmetal valve element 54 is provided connected to the first side of thepiston 40 and is adapted to seat on the first valve seat 50 to provide apositive seal when the piston 40 moves away from the first valve seat 50(FIG. 1). A second metal valve elements 56 is connected to the secondside of the piston 40 and is adapted to seat on the second valve seat 52and provide a positive seal when the piston 40 moves away from thesecond valve seat 52 (FIG. 2). Preferably, the valve element 54 and 56are connected to the piston 40 by a ball and socket universal connection58 and 60, respectively, for allowing the piston 40 to align itselfproperly in the cylinder 48 without binding. The piston 40 merelyprovides a dynamic seal in the cylinder 48 sufficient to cause movementof the piston 40 in the cylinder 48 to actuate the sliding tube 22. Thevalve elements 54 and 56 provide a static and positive seal when theyare seated on their respective valve seats 50 and 52. Therefore, withthe use of the positive valve elements 54 and 56 leakage of fluids pastthe piston 40 will not cause the hydraulic actuating system to becomeinoperative so long as the piston 40 seals sufficiently in the cylinder48 to move the valve elements 54 and 56 to their seated positions. Oncethe valve elements 54 and 56 are in the seated position, fluid pressureacting on the back side of the elements 54 and 56 will positively seatand keep the valve elements 54 and 56 seated. The piston 40 may be inthe form 41 shown in FIG. 3A which is a conventional turbulent orlabyrinth seal which has a minimum of sealing action. In fact the piston40 could be merely a smooth elongated rod with a sufficiently close fitin the cylinder 48 whereby the pressure drop acting across the pistonwould move the valve elements 54 and 56 into their seated position.

Referring to FIG. 3, an exploded perspective view of two hydraulicpiston and cylinder actuators are shown which are identical and whereinthe numbers of the second actuating means utilize the suffix "a" tocorrespond to like parts. Thus, the cylinders 48 and 48a are threadablysecured at their upper ends to a housing member 13 and are enclosed bysemi-circular housing members 15, which are secured to member 13 bysuitable bolts 17.

In operation, when hydraulic control fluid is supplied through the line32 fluid will flow into the passageway 46 and into the cylinder 48 abovethe piston 40 moving the piston 40 downwardly which in turn carries thesliding tube 22 downwardly to open the flapper 18. Downward movement ofthe piston 40 carries the valve element 54 downwardly until it contactsand seats on valve seat 50 (FIG. 1) to provide a positive seal andfurther fluid pressure in the fluid passageway 46 acts on the back ofthe valve element 54 to hold it in the sealed position. When it isdesired to close the valve, the pressure in the hydraulic control line32 is reduced thereby reducing the pressure in the hydraulic passageway46 and on the top of the valve element 54. The fluid pressure in thebore 14 of the safety valve 10 is in communication with the cylinder 48and the bottom of the piston 40 and along with the spring 26 biases thepiston 40 in an upward direction until, as best seen in FIG. 2, thevalve element 56 is seated on the valve seat 52 to provide a positiveseal in the upward direction. Thereafter, the fluid pressure in the welltubing and bore 14 acts on the back of the valve element 56 to maintainit in a sealed position on the valve seat 52.

Other and further embodiments of a hydraulic actuating means may beprovided utilizing a metal piston movable in a cylinder and connected tothe valve closure member. Spaced metal valve seats in the cylinder andmetal valve elements connected to the piston which will provide apositive seal in both directions for the double acting piston. Thisavoids the use of elastomer seals and can be utilized in both high andlow pressure and high and low temperature applications. Referring now toFIG. 4, another embodiment of the present invention is shown in whichlike parts to those in FIG. 2 are similarly numbered with the suffix"b". Referring now to FIG. 4, the cylinder 48b includes a first metalvalve seat 50b on one side of the piston 40b. A second metal valve seat52b is provided on the cylinder 48 on the same side of the piston 40b asthe valve seat 50b. A first metal valve element 54b is providedconnected to said one side of the piston 40b and is adapted to set onthe first valve seat 50b to provide a positive seal when the piston 40bmoves downwardly and towards the first valve seat 50b. A second metalvalve element 56b is connected to said one side of the piston 40b and isadapted to seat on the second valve seat 52b and provide a positive sealwhen the piston 40b moves upwardly and away from the second valve seat52b. Preferably, the valve elements 54b and 56b are connected to thepiston 40b by a ball and socket universal connection 58b. In addition, acentralizer 49 may be provided connected by a ball and socket universalconnection 60b on the second side of the piston 40b for aligning thepiston 40b in the cylinder 48b. As in the prior embodiment, the piston40b merely provides a dynamic seal in the cylinder 48b sufficient tocause movement of the piston 40b in the cylinder 48b to actuate thesliding tube 22. The valve elements 54b and 56b provide static andpositive seals when they are seated on the respective valve seats 50band 52b. Once the valve element 54b or 56b are in the seated position,the fluid pressure acting on the back side of the elements 54b and 56bwill positively seat and keep the valve elements 54b and 56b seated.Again, the piston 40b may be of the opposing metal cup type or alabyrinth seal 41 shown in FIG. 3A or even a smooth elongated rod havinga sufficiently close fit in the cylinder 48b to provide a pressure dropsufficient to move the valve elements 54b and 56b into their seatedposition. The operation of the hydraulic actuating mechanism of FIG. 4is similar to that described in connection with the operation of theactuator in FIGS. 1-3.

The present invention, therefore, is well adapted to carry out theobjects and attain the ends and advantages mentioned as well as othersinherent therein. While presently preferred embodiments of the inventionare given for the purpose of disclosure, numerous changes in the detailsof construction and arrangement of parts, will readily suggestthemselves to those skilled in the art and which are encompassed withinthe spirit of the invention and the scope of the appended claims.

What is claimed is:
 1. In a well safety valve for controlling the fluidflow through a well conduit and including a housing and a valve closuremember moving between open and closed positions, a longitudinal tubularmember telescopically movable in the housing for controlling themovement of the valve closure element, the improvement in hydraulicactuating means for actuating the valve closure member comprising,acylinder in the housing, a metal piston movable in the cylinder inresponse to fluid acting on the piston, said piston connected to andmoving the tubular member, said cylinder on one side of the piston incommunication with a hydraulic control fluid passageway, and saidcylinder on the second side of the piston in communication with pressurein the safety valve, said cylinder including first and second spacedmetal valve seats, and first and second metal valve elements connectedto the piston, said first and second elements spaced from each other toalternately seat and unseat on the first and second valve seats,respectively, as the piston alternately moves in the cylinder.
 2. Theapparatus of claim 1 wherein the first and second valve seats are onopposite sides of the piston and the first and second valve elements areconnected to opposite sides of the piston.
 3. The apparatus of claim 1where in the valve seats and valve elements are positioned whereby thefirst element is adapted to seat on the first seat when the piston movesaway from the first seat, and the second element is adapted to seat onthe second seat when the piston moves away from the second seat.
 4. Theapparatus of claim 1 wherein the first and second valve seats arepositioned on one side of the piston and the first and second valveelements are connected to said one side of the piston.
 5. The apparatusof claim 1 wherein the piston includes opposing metal cups engaging saidcylinder.
 6. The apparatus of claim 1 wherein the piston includes alabyrinth seal.
 7. The apparatus of claim 1 including,a universalconnection between the first and second sides of the piston and saidvalve elements.
 8. In a well subsurface safety valve for controlling thefluid flow through a well conduit and including a tubular housing havingan axial bore therethrough and a valve closure member moving betweenopen and closed positions for controlling the fluid flow through thebore, a longitudinal tubular member telescopically moving in the housingcoaxially with the bore for controlling the movement of the valveclosure member, the improvement in hydraulic actuating means foractuating the valve closure member comprising,a generally longitudinallyextending cylinder in the housing, said cylinder having its upper end incommunication with a hydraulic control fluid passageway, and saidcylinder having its lower end in communication with the pressure in theaxial bore of the safety valve, a metal piston movable in the cylinderin response to fluid movement through the cylinder acting on and movingsaid piston, said piston connected to and moving said tubular member,said cylinder including an upper metal valve seat at the upper end ofthe cylinder and including a lower metal valve seat at the lower end ofthe cylinder, an upper metal valve element connected to the piston andpositioned above the upper valve seat and adapted to seat on the uppervalve seat when the piston moves downwardly away from the upper valveseat, and a lower metal valve element connected to the piston andpositioned below the lower valve seat and adapted to seat on the lowervalve seat when the piston moves upwardly away from the lower valveseat.
 9. The apparatus of claim 8 wherein said piston includes opposingmetal cups engaging said cylinder.
 10. The apparatus of claim 8 whereinsaid piston includes a labyrinth seal.
 11. The apparatus of claim 8including,a universal connection between the first and second sides ofthe piston and said valve elements.
 12. In a well subsurface safetyvalve for controlling the fluid flow through a well conduit andincluding a tubular housing having an axial bore therethrough and avalve closure member moving between open and closed positions forcontrolling the fluid flow through the bore, a longitudinal tubularmember telescopically moving in the housing coaxially with the bore forcontrolling the movement of the valve closure member, the improvement inhydraulic actuating means for actuating the valve closure membercomprising,a generally longitudinally extending cylinder in the housing,said cylinder having its upper end in communication with a hydrauliccontrol fluid passageway, and said cylinder having its lower end incommunication with the pressure in the axial bore of the safety valve, ametal piston movable in the cylinder in response to fluid movementthrough the cylinder acting on and moving said piston, said pistonconnected to and moving said tubular member, said cylinder including afirst metal valve seat and a second metal valve seat on one side of thepiston, a first metal valve element connected to one side of the pistonadapted to seat on the first valve seat when the piston moves away fromthe first valve seat, and a second metal valve element connected to theone side of the piston and adapted to seat on the second valve seat whenthe piston moves towards the second valve seat.
 13. The apparatus ofclaim 12 wherein said piston includes opposing metal cups engaging saidcylinder.
 14. The apparatus of claim 12 wherein the piston includes alabyrinth seal.
 15. The apparatus of claim 12 including,a universalconnection between the piston and said valve elements. .Iadd.
 16. In awell safety valve for controlling the fluid flow through a well conduitand including a housing and a valve closure member moving between openand closed positions, a longitudinal tubular member telescopicallymovable in the housing for controlling the movement of the valve closureelement, the improvement in a hydraulic actuating means for actuatingthe valve closure member comprising,a cylinder in the housing, a pistonmovable in the cylinder in response to fluid acting on the piston, saidpiston contacting and moving the tubular member, said cylinder on oneside of the piston in communication with a hydraulic control fluidpassageway, and said cylinder on the second side of the piston incommunication with pressure in a safety valve, said cylinder includingfirst and second spaced metal valve seats, and first and second metalvalve elements connected to the piston, said first and second elementsspaced from each other to alternately seat and unseat on the first andsecond valve seats, respectively, as the piston alternately moves in thecylinder. .Iaddend. .Iadd.
 17. In a subsurface well safety valve forcontrolling the fluid flow through a well conduit and including ahousing having a bore and a valve closure member moving between open andclosed positions for controlling the fluid flow through the bore, atubular member telescopically moving in the housing for controlling themovement of the valve closure member, and biasing means for moving thetubular member in a direction to close the valve, the improvement influid actuating means for actuating the valve closure membercomprising,a cylinder in the housing, a piston in and movable relativeto the cylinder in response to fluid pressure in the cylinder, one ofsaid cylinder and piston engaging and moving the tubular member, saidcylinder on one side of the piston adapted to be in communication with afluid control passageway, and said cylinder on the second side of thepiston adapted to be in communication with a biasing fluid, first andsecond metal valve seats on one of the piston and cylinder, and firstand second valve elements which coact with the first and second seats,respectively, said valve elements being on the other of the piston andcylinder, and said first seat and first valve element positioned to shutoff flow from the fluid control passageway to the cylinder when thesafety valve is in one of said open and closed positions, and saidsecond seat and second valve element positioned to shut off flow of thebiasing fluid to the cylinder when the safety valve is in the other ofsaid open and closed positions. .Iaddend.